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https://issues.apache.org/jira/browse/DRILL-5797?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16540053#comment-16540053
]
ASF GitHub Bot commented on DRILL-5797:
---------------------------------------
arina-ielchiieva commented on a change in pull request #1370: DRILL-5797: Use
Parquet new reader in all non-complex column queries
URL: https://github.com/apache/drill/pull/1370#discussion_r201676485
##########
File path:
exec/java-exec/src/main/java/org/apache/drill/exec/store/parquet/ParquetReaderUtility.java
##########
@@ -140,15 +142,88 @@ public static int getIntFromLEBytes(byte[] input, int
start) {
return out;
}
+ /**
+ * Map full schema paths in format `a`.`b`.`c` to respective SchemaElement
objects.
+ *
+ * @param footer Parquet file metadata
+ * @return schema full path to SchemaElement map
+ */
public static Map<String, SchemaElement>
getColNameToSchemaElementMapping(ParquetMetadata footer) {
- HashMap<String, SchemaElement> schemaElements = new HashMap<>();
+ Map<String, SchemaElement> schemaElements = new HashMap<>();
FileMetaData fileMetaData = new
ParquetMetadataConverter().toParquetMetadata(ParquetFileWriter.CURRENT_VERSION,
footer);
- for (SchemaElement se : fileMetaData.getSchema()) {
- schemaElements.put(se.getName(), se);
+
+ Iterator<SchemaElement> iter = fileMetaData.getSchema().iterator();
+
+ // First element in collection is default `root` element. We skip it to
maintain key in `a` format instead of `root`.`a`,
+ // and thus to avoid the need to cut it out again when comparing with
SchemaPath string representation
+ if (iter.hasNext()) {
+ iter.next();
+ }
+ while (iter.hasNext()) {
+ addSchemaElementMapping(iter, new StringBuilder(), schemaElements);
}
return schemaElements;
}
+ /**
+ * Populate full path to SchemaElement map by recursively traversing schema
elements referenced by the given iterator
+ *
+ * @param iter file schema values iterator
+ * @param path parent schema element path
+ * @param schemaElements schema elements map to insert next iterator element
into
+ */
+ private static void addSchemaElementMapping(Iterator<SchemaElement> iter,
StringBuilder path,
+ Map<String, SchemaElement> schemaElements) {
+ SchemaElement schemaElement = iter.next();
+ path.append('`').append(schemaElement.getName().toLowerCase()).append('`');
+ schemaElements.put(path.toString(), schemaElement);
+
+ int remainingChildren = schemaElement.getNum_children();
Review comment:
Please add comment why remaining children are important in while loop.
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> Use more often the new parquet reader
> -------------------------------------
>
> Key: DRILL-5797
> URL: https://issues.apache.org/jira/browse/DRILL-5797
> Project: Apache Drill
> Issue Type: Improvement
> Components: Storage - Parquet
> Reporter: Damien Profeta
> Assignee: Oleksandr Kalinin
> Priority: Major
> Fix For: 1.15.0
>
>
> The choice of using the regular parquet reader of the optimized one is based
> of what type of columns is in the file. But the columns that are read by the
> query doesn't matter. We can increase a little bit the cases where the
> optimized reader is used by checking is the projected column are simple or
> not.
> This is an optimization waiting for the fast parquet reader to handle complex
> structure.
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